Improvement in low-temperature fixing ability of the toner is desired, from the viewpoint of conservation of energy, shortening of idling time, miniaturization of the apparatus, or the like. In view of the above, one technique for improving low-temperature fixing ability is a technique in which a crystalline resin and an amorphous resin that rapidly melt at a fixing temperature are used as binder resins, and the crystalline polyester is contained in an amount of 1 to 40% by weight of the resin binder, and 90% or more of the dispersed domain of the crystalline polyester in the toner is adjusted to a diameter of from 0.1 to 2 μm (see JP-A-2002-287426). Moreover, as a method of adjusting a diameter of the dispersed domain of a crystalline polyester in the toner, a method of adjusting softening temperatures of a crystalline polyester and an amorphous resin, kneading conditions upon the toner production, or the like is proposed.
In addition, for the purpose of obtaining a toner having excellent low-temperature fixing ability, offset resistance, and durability, favorable resolution, and providing high-quality image free from background fogging or unevenness in image densities, there is a technique of adjusting the maximum particle size of the dispersed domain of the crystalline polyester in the toner so that the major axis diameter is 0.5 μm or more, and that the maximum particle size of dispersed domain is ½ or less than the maximum particle size of the toner (see JP-A-2004-279476). Moreover, in order to adjust the particle size of the dispersed domain of the crystalline polyester in the toner, the crystalline polyester fed to a kneader in the step of kneading toner raw materials is formed into fine particles.